Final report for LNE18-365
Project Information
Growers consistently identify management of insect pests of brassicas as a major production challenge and priority for research and education. Recent increases in production and season length has intensified pressure from a suite of perennial insect pests including cabbage maggots, cabbage aphids, flea beetles, several caterpillar species, and new emerging pests including Swede midge and cabbage whitefly. Successful brassica pest control necessitates a high level of understanding of pest life cycles and integration of multiple strategies. This can be difficult and time-consuming to achieve and many growers lack confidence in the controls available or their ability to implement them, and struggle to produce quality brassica crops. The Brassica Pest Collaborative was a network of researchers, growers, and ag service providers that was formed to investigate new and improved methods for improving pest control, quality, and yield of brassicas. Through our research we: identified the most effective OMRI-approved insecticides and new reduced-risk insecticides for flea beetles and cabbage root maggots; determined the efficacy of mulches and exclusion netting to reduce damage from flea beetles and root maggots; conducted a survey to identify aphidophagous syrphid flies in the Northeast; determined the relative attractiveness of different insectary flowers to a parasitoid of cabbage aphids; tested the efficacy of beneficial nematodes to control flea beetles; and showed that Ammi majus can be used to attract parasitoids of caterpillar pests. Information on pest biology and management was shared through web-based trainings, and in-field demonstrations highlighted research findings. Timely pest alerts were shared through our traditional Extension newsletters. Growers were supported to adopt or improve management strategies through one-on-one technical assistance and web-based trainings and resources. Through these efforts, at least 42 growers managing at least 124 acres adopted or improved pest control strategies and improved pest control by 43%, increased quality by 49% and increased yield and profits by 44 and 42%, respectively.
Performance target: Fifty brassica growers adopt or improve ecological pest management approaches including scouting, cultural practices, conservation biocontrol, and use of reduced-risk pesticides on 500 acres, reducing crop damage, increasing marketable yield, and increasing annual gross revenue by $500,000.
Growers consistently identify management of insect pests of brassicas as a major production challenge and priority for research and education (UMass Extension Stakeholder Meeting Notes 2017, 2016, 2015). Nearly 9,000 vegetable farmers across New England and NY grow approximately 15,000 acres of brassica crops. On most mixed vegetable operations around the Northeast, brassica crops make up a very large percentage of the total crop mix and total acreage, and are now also commonly grown throughout the winter to satisfy unceasing consumer demand for local, leafy greens. This increase in production and season length has intensified pressure from a suite of perennial insect pests including cabbage maggots, cabbage aphids, flea beetles, several caterpillar species, and new emerging pests including Swede midge and cabbage whitefly. Successful brassica pest control necessitates a high level of understanding of pest life cycles and integration of multiple strategies. This can be difficult and time-consuming to achieve and many growers lack confidence in the controls available or their ability to implement them, and struggle to produce quality brassica crops.
A regional, collaborative research and education program is necessary to improve management of this suite of insect pests. Our educational efforts helped growers increase their knowledge of brassica pest biology and increase confidence in implementing best management practices by 1) participating in web-based educational opportunities with experts from around the region through a Brassica Pest Collaborative and 2) attending in-person and virtual field day demonstrations where key individuals will share their experiences implementing new and alternative control strategies. Our research program evaluated the efficacy of tactics like mulches, netting, and conservation biocontrol to combat multiple pests, reduce overall pest damage, and increase yield. Constraints like labor and time were addressed by using cost to benefit analyses to help growers to identify new ways to increase profits growing brassicas. By coordinating research efforts, we were able to tackle a wide range of topics with a high degree of rigor, as treatments and protocols were standardized and results were considered together across site-years, leading to the submittal of one academic paper for publication.
Our education program focused on giving growers the knowledge and confidence they need to be successful implementing current best management practices, and supported them in incorporating cultural practices and conservation biocontrol strategies listed above on their farms. Education efforts included improving grower understanding of pest life cycles, which help them to better utilize crop rotations to disrupt pest life cycles, improve timing and efficacy of sprays, apply and remove netting only when needed, and so on. We also developed resources to help growers identify pest and beneficial insects, scouting protocols and recordkeeping sheets to facilitate monitoring of pest populations and crop damage over time, so that they can keep track of their progress.
Our research program furthered our scientific understanding of the efficacy and impacts of cultural practices and conservation biocontrol strategies, as well as the efficacy of organic-compatible and/or reduced risk alternative chemical control options. Through our research trials, which were designed in collaboration with actual growers on the advisory board, we demonstrated practical application of these methods. This empowered growers to begin to implement these more time-consuming and labor-intensive preventive practices.
Several experiments were conducted to test the following hypotheses: 1) reduced-risk and organic-compatible pesticides effectively control brassica pest populations 2) cultural practices (e.g. netting, mulches, and residue management) disrupt pest life cycles and reduce crop damage; 3) conservation biocontrol strategies attract predators and parasitoids of brassica pests, reducing pest population size and crop damage and 4) integration of these approaches improves control of multiple pests and increases marketable yields of brassica crops.
Cooperators
- (Educator and Researcher)
- (Researcher)
- (Educator and Researcher)
- (Educator and Researcher)
- (Educator and Researcher)
Research
Ecological management approaches reduce insect populations and crop damage, increasing marketable yield of brassica crops.
Several experiments will be conducted to test the following hypotheses:
1) reduced-risk and organic-compatible pesticides effectively control brassica pest populations
2) cultural practices (e.g. netting, mulches, and residue management) disrupt pest life cycles and reduce crop damage;
3) conservation biocontrol strategies attract predators and parasitoids of brassica pests, reducing pest population size and crop damage and
4) integration of these approaches improves control of multiple pests and increases marketable yields of brassica crops.
Reports can be found on our website at: https://ag.umass.edu/vegetable/resources-services/brassica-pest-collaborative/research-reports-on-management-of-brassica
Hypothesis 1: Reduced-risk and organic-compatible pesticides effectively control brassica pest populations.
2018
"Foliar Insecticides for Control of Cabbage Flea Beetles in Cabbage and Pak choy," by F. Zaman and D. Gilrein in NY.
In this study, several conventional and OMRI-listed organic insecticides were compared for control of flea beetles (Phyllotreta cruciferae Goeze) in fresh-market cabbage and pak choy production. Materials tested included one rate each of Entrust SC (spinosad 1SC, Dow Agrosciences, OMRI-listed = Organic Materials Review Institute), Surround WP (95% kaolin, Tessenderlo, OMRI), PyGanic 5.0 (5% pyrethrins, Valent/MGK, OMRI), M-Pede (49% potassium salts of fatty acids, Gowan, OMRI), SuffOil-X (80% mineral oil, BioWorks, OMRI), Molt-X (azadirachtin 0.28EC, BioWorks, OMRI), Assail 30SG (acetamipridm UPI), Warrior II (lambda-cyhalothrin 2.08EC, Syngenta), and Harvanta 50SL (cyclaniliprole 0.42SL, Summit Agro). Unsprayed blocks were used as a control for both crops.
Treatments were compared in two large-plot field experiments on transplanted “Cheers” cabbage and pak choy at the Long Island Horticulture Research and Extension Center (LIHREC) in Riverhead, NY. On June 5 and July 7, 2018, respectively, cabbage and pak choy seeds were sowed in Speedling trays. Trays were maintained on a greenhouse bench with overhead irrigation as needed including a commercial soluble fertilizer (15-5-15 Cal-Mg, 150 ppm N, Jack’s Professional). On July 17 (cabbage) and August 6 (pak choy) seedlings were transplanted to the field spaced 11” apart in 34” rows in the main field at LIHREC. Four 30’ rows (approximately 340 sq. ft.) per replication and four replications per treatment were used for both experiments. One day after transplanting the area was treated with Devrinol 50DF (2 lbs/A) for weed control. Treatments were assigned randomly to plot, arranged in a randomized complete block design. Treatments were applied as foliar sprays to wet using a CO2-powered backpack sprayer fitted with TJ60 8003EVS nozzles operating at 40 psi. Treatments were applied at 10-day intervals on 7/27, 8/6, and 8/15 for cabbage and at weekly intervals on 8/10, 8/17, and 8/23 for pak choy. Number of cabbage flea beetles, flea beetle damage ratings (Ohio Scale, 1 - 6), and % foliage feeding damage from flea beetles (0 – 100%) to new growth (since previous application) were taken from 10 randomly selected plants per replication at a weekly interval from 7/25 to 8/30 in cabbage and 8/10 to 8/30 in pak choy. Plant quality data at harvest were collected including head diameter and weight for cabbage on 10/3 and above-ground plant height, width, and weight for pak choy on 9/7, respectively. Marketable quality ratings (0 – 5, 0 = dead plants, 3 = marketable, 5 = excellent) were done at harvest for both crops. ANOVA and multiple comparisons among treatments were performed on data using Tukey’s HSD (JMP Pro 10.0 SAS Institute). Treatments and data are shown in Tables 1 - 8 in the report posted online.
"Beneficial Nematodes to Reduce Flea Beetle Population Size" was conducted by M. Meder, G. Higgins and S. Scheufele in MA.
Flea beetle adults lay their eggs at the base of brassica plants after mating. The eggs hatch and larvae feed on the fine roots for several weeks, pupate, and adults re-emerge from the soil to find new brassica leaf tissue to eat. Studies have shown that nematodes in the families Steinermena and Heterorhabditidae can attack the larval stage of flea beetles in the soil, thereby reducing the overall size of the population within a field over time. We wanted to know if this strategy would cause noticeable reductions in flea beetle populations in a real field. We used a mixture of Steinermena carpocapsae plus Heterorhabditis bacteriophora nematodes applied to the soil as a drench at the base of the plants and monitored adult flea beetle emergence from the soil over the following 5 weeks.
Our treatments were:
1. Untreated control
2. Low rate 5 x 107 nematodes/2500 sq. ft. (600,000 nematodes per plot)
3. High rate 5 x 107 nematodes/1000 sq. ft. (1,500,000 nematodes per plot)
4. Entrust SC at 10 fl oz/A ( the labeled rate for root maggot suppression via soil application)
‘Green Magic’ broccoli (Johnny’s Selected Seeds, ME) was started in the greenhouse on April 24. On June 24th 100# N/A organic fertilizer (7-2-4) was applied and broccoli was transplanted by hand into staggered double rows 18 in. apart and 11 in. in-row spacing. One line of drip tape was used to maintain adequate soil moisture but no mulch was used, so that we could later apply treatments to the soil and could monitor adult flight out of the soil. Borisol was applied on June 1, 8, and 30th. We ordered commercial nematodes from Koppert Biological Systems and on June 15th, the nematodes were re-constituted in water and we looked at the solution under the microscope to ensure the nematodes were alive and to quantify them accurately. We also checked that the treatment application method was not lethal to the nematodes by spraying the solution into a beaker and re-checking the percentage of living versus dead nematodes in the sprayed solution. The field was divided up into four replications of each of the four treatments, with plots consisting of 10 ft. of bed with a 5 ft. buffer in between. We then applied the treatments using a CO2-powered backpack sprayer with a Floodjet nozzle (TeeJet TK-7.5) and no filter, set to 15 PSI. We then setup emergence cages, which consisted of no-se’em netting sewn into a tube with 1 ft. diameter metal ring base, over individual broccoli plants to capture flea beetles as they emerge from the soil below over time. We monitored emergence of the adult beetles by placing a yellow sticky card inside the trap and checking the card once per week and recording the numbers of beetles present over time. We also happened to capture cabbage root maggot flies emerging on some days. There was one trap per plot. No harvest or yield data was recorded because the plants were damaged from heat waves that occurred during head formation and most crowns were not marketable.
2019
Both studies from 2018 were repeated with slight variations in methods and results.
"Foliar Insecticides for Control of Cabbage Flea Beetles in Cabbage and Pak choy."
In 2019, the foliar insecticides for flea beetle control was repeated nearly identically, using pak choy as the host crop. On August 22 (pak choy) seedlings were transplanted to the field spaced 11” apart in 34”. Four 30’ rows (approximately 340 sq. ft.) per replication and four replications per treatment were used for the experiment. Because of the high crucifer flea beetle population in the area at the time of transplanting, a twice per week treatment schedule was followed for the first 3 applications and a 4th (final) application was applied at 7 days after the 3rd application.
"Beneficial Nematodes to Reduce Flea Beetle Population Size."
In 2019, the study entitled "Beneficial Nematodes to Reduce Flea Beetle Population Size" was repeated following the same methods as in 2018 except that we doubled the number of emergence traps in order to increase the statistical power. We used two traps per plot, with five replications of each of the four treatments. Broccoli seedlings were transplanted on 28 May and nematodes were applied on 14 June, except for Heterorhabditis bacteriophora because the nematodes were not living when we inspected them in the lab. The H. bacteriophora were re-ordered and applied on 18 June. We maintained moist field conditions using drip irrigation and monitored emergence of adult FB using yellow sticky cards placed within the netted emergence traps.
"Organic and reduced-risk practices for control of cabbage root maggot"
This study included treatments from hypothesis 1--reduced-risk pesticides--and hypothesis 2--cultural practices. Several conventional and organic insecticides and other alternative methods were compared for control of cabbage maggot (Delia radicum) in fresh-market cabbage. Treatments tested included insecticides Verimark 1.67SC (cyantraniliprole, FMC) at 13.5 fl. oz/A, Entrust SC (spinosad, Corteva) at 8.0 fl. oz/A, Radiant 1SC (spinetoram, Corteva) at 10.0 fl. oz/A, Tek-Knit exclusion netting (80-gram) over a black plastic mulch planting bed, and black plastic mulch planting bed alone. Lorsban 75WG (chlorpyrifos, Gowan) at 1.8 oz/1000 ft row was used as a standard for comparison. Verimark, Entrust and Radiant were applied as a pre-plant transplant tray drench and followed by one directed application two weeks after transplanting. Lorsban was applied in a 4-inch band spray over the furrow 7 days after planting. Untreated plots were used as a control.
This trial was conducted from mid-April to August 30, 2019. On April 12th ‘Bravo’ cabbage was sown into Speedling transplant trays using a standard peat-based media (Pro-Mix BX with Mycorrhizae, Premier Horticulture Inc.). Plants were maintained in a greenhouse on overhead watering as needed including a commercial fertilizer (15-5-15 Cal-Mg, 150 ppm N Jack’s Professional). On May 24 plants were transplanted 11” apart in 34-inch rows in the main field except for black plastic mulch rows, where plants were set on a 31-inch wide bed in rows spaced 18” and 15” apart in an alternate planting design. For exclusion netting plots, 18-inch row spacing allows about 6.5-inch clearance between plants and sidewall of the net coverings. Four rows 30 feet long (approximately 340 sq. ft.) per replication and four replications per treatment were used. Insecticide treatments were applied using a CO2-powered backpack sprayer fitted with a TJ60 4003EVS nozzle operating at 20 psi. Pre-plant tray drenches were applied to transplants 24 hours prior to setting in the main field. Post-transplant targeted applications were made two weeks after transplanting, directing spray to the lower stems and soil at the base of plants. Exclusion netting rowcover was set within 24 hours following transplanting of the 6-week old cabbage seedlings in 2” x 2” holes on black plastic mulch and rows remained covered until harvest. Where black plastic mulch was used alone, plants were set in a similar way to those in the exclusion net+ mulch treatment. Transplant flat rates for tray drench treatments were calculated to provide an amount of active ingredient per plant equivalent to the field rate per plant, using 500 ml water per 26 5/8" x 13 5/8” (200 cell) tray. Lorsban 75WG was applied per label in 64 gal water per acre as a 4-inch banded spray to soil at the base of plants immediately after setting (within 7 days of transplanting). Plants were watered lightly after transplanting and as needed afterwards. Drip tape irrigation was used both black plastic mulch plots. The other plots were irrigated by overhead sprinkler system. Fertilizer was applied at 500 lb/A rate prior to planting and no herbicides were used in either plastic mulch treatment. On June 24 cabbage maggot damage was evaluated (presence or absence of cabbage maggot damage and severity in roots) by digging up 20 randomly selected plants from the middle two rows of each plot (80 plants per treatment), then washing and inspecting for cabbage maggot damage (gallery or tunneling in main root) and rating severity (based on number and length of feeding marks) on a 0 – 10 scale (0 = no damage, 3 = moderate, 5 – 7 = high, 8 – 9 = extreme, 10 = plant dead). The percent damaged plants and mean damage severity were calculated for each treatment. Stem diameter at the soil line, cabbage head weight and diameter at harvest, foliage feeding by other insects, and marketable head quality were also measured (1 = 5 scale, 1 = poor quality, 3 = marketable, 5 = excellent). ANOVA and multiple comparisons among treatments were performed on raw data using the Tukey’s HSD (JMP Pro 14.0, SAS Institute). Treatments and data are shown in Figure 1 to 7.
2020
"Organic and reduced-risk practices for control of cabbage root maggot"
The cabbage maggot control study from 2019 was repeated, with several conventional and organic insecticides and other alternative methods being compared for control of cabbage maggot (Delia radicum) in fresh-market cabbage. Treatments tested included insecticides Verimark 1.67SC (cyantraniliprole, FMC) at 13.5 fl. oz/A, Entrust SC (spinosad, Corteva) at 8.0 fl. oz/A, Radiant 1SC (spinetoram, Corteva) at 10.0 fl. oz/A, Tek-Knit exclusion netting (80-gram) over a black plastic mulch planting bed, and black plastic mulch planting bed alone. Lorsban 75WG (chlorpyrifos, Gowan) at 1.8 oz/1000 ft row was used as a standard for comparison. Verimark, Entrust and Radiant were applied as a pre-plant transplant tray drench and followed by one directed application two weeks after transplanting. Lorsban was applied in a 4-inch band spray over the furrow 7 days after planting. Untreated plots were used as a control.
This trial was conducted from mid-April to August 30, 2020. On April 2nd ‘Bravo’ cabbage was sown into Speedling transplant trays using a standard peat-based media (Pro-Mix BX with Mycorrhizae, Premier Horticulture Inc.). Plants were maintained in a greenhouse on overhead watering as needed including a commercial fertilizer (15-5-15 Cal-Mg, 150 ppm N Jack’s Professional). On May 11th about six weeks old seedlings were transplanted 11” apart in 34-inch rows in the main field except for black plastic mulch rows, where plants were set on a 31-inch wide bed in rows spaced 18” and 15” apart in an alternate planting design. For exclusion netting plots, 18-inch row spacing allows about 6.5-inch clearance between plants and sidewall of the net coverings. Four rows 30 feet long (approximately 340 sq. ft.) per replication and four replications per treatment were used for insecticides and control treatments. Two 100 ft long rows per replication (4 replications/treatment) were planted for exclusion netting and black plastic mulch treatments. Insecticide treatments were applied using a CO2-powered backpack sprayer fitted with a TJ60 4003EVS nozzle operating at 20 psi. Pre-plant tray drenches were applied to transplants 24 hours prior to setting in the main field. Post-transplant targeted applications were made two weeks after transplanting, directing spray to the lower stems and soil at the base of plants. Exclusion netting rowcover was set within 24 hours following transplanting of the 6-week old cabbage seedlings in 2” x 2” holes on black plastic mulch and rows remained covered until harvest. Where black plastic mulch was used alone, plants were set in a similar way to those in the exclusion net+ mulch treatment. Transplant flat rates for tray drench treatments were calculated to provide an amount of active ingredient per plant equivalent to the field rate per plant, using 500 ml water per 26 5/8" x 13 5/8” (200 cell) tray. Lorsban 75WG was applied per label in 64 gal water per acre as a 4-inch banded spray to soil at the base of plants immediately after setting (within 7 days of transplanting). Plants were watered lightly after transplanting and as needed afterwards. Drip tape irrigation was used both black plastic mulch plots. The other plots were irrigated by overhead sprinkler system. Fertilizer was applied at 500 lb/A rate prior to planting and no herbicides were used in either plastic mulch treatment. On June 10 cabbage maggot damage was evaluated (presence or absence of cabbage maggot damage and severity in roots) by digging up 20 randomly selected plants from the middle two rows of each plot (80 plants per treatment), then washing and inspecting for cabbage maggot damage (gallery or tunneling in main root) and rating severity (based on number and length of feeding marks) on a 0 – 10 scale (0 = no damage, 3 = moderate, 5 – 7 = high, 8 – 9 = extreme, 10 = plant dead). The percent damaged plants and mean damage severity were calculated for each treatment. Stem diameter at the soil line, cabbage head weight and diameter at harvest, foliage feeding by other insects, and marketable head quality were also measured (1 = 5 scale, 1 = poor quality, 3 = marketable, 5 = excellent). ANOVA and multiple comparisons among treatments were performed on raw data using the Tukey’s HSD (JMP Pro 14.0, SAS Institute). Treatments and data are shown in Figure 1 to 8.
Hypothesis 2: Cultural practices (e.g. netting, mulches, and residue management) disrupt pest life cycles and reduce crop damage.
"Using Mulches to Reduce Flea Beetle Damage and Improve Crop Yield"
2018: In previous brassica pest management trials we had observed a marked decrease in flea beetle damage in plants grown in certain types of mulches. In these cases, the mulched plants were much more vigorous than those growing on bare ground, and could be identified from across the field for their greater size, and reduced damage from flea beetles. This was never the focus of study and so we did not collect data on flea beetle damage at the time, but decided to investigate this effect in a replicated trial in 2018. We set out to determine:
1. if mulches can reduce flea beetle damage to brassica crops,
2. if mulches can increase crop quality and/or yield, and
3. which mulches are best at reducing damage and increasing quality and yield
We compared six different mulch treatments, with each treatment replicated four times. We formed raised beds and laid mulches by hand over one line of drip tape. Plastic and paper mulches were secured with soil along the edges. Straw mulch was applied to a depth of 4”. Soil temperature monitors were buried 2” below the soil surface and under the mulch cover.
Four-week old ‘Arcadia’ broccoli seedlings were planted into two rows at 10” between plants and 12” between rows on July 6th. Fertilizer was applied according to soil test results. The plot was irrigated twice in early July but subsequent rainy weather precluded need for further irrigation. On August 3rd, all plants were sprayed with Dipel (1 lb/A) and M-Pede (2% v/v) to control caterpillar pests and aphids.
Each week we rated:
• Flea beetle pressure (# beetles/plant)
• Flea beetle damage, using the following scale: 0=0%; 1=0-10%; 2=11-25%; 3=26-50%; 4=>50%
• Whole plot vigor: a visual assessment of stand, plant size, and leaf color (0-100%)
• Plant height
Once the crop was established (5 weeks after planting) we stopped rating until the crop was ready to harvest and yield data was collected. Because of erratic temperatures and heavy rains, broccoli heads developed very unevenly and we had very few marketable crowns. Therefore, we harvested entire plants by clipping the stem at the soil line and measured the total plant weight per plot, in order to capture the difference in plant growth observed across the mulch treatments.
2019: This mulch study was repeated three times in 2019, but using different crop hosts and planting timings. We wanted to evaluate the effect of mulches on bok choy, and during the spring flush of FB and therefore the experiment was setup in spring using bok choy but the crop was too susceptible and there were no differences between treatments--all plants were severely damaged. Thus we set the experiment up again in the fall, using both bok choy and broccoli, in order to repeat both. However, the bok choy was again so susceptible that the damage was too high to see any treatment differences. Furthermore, the FB were so attracted to the bok choy that there was no damage at all in the nearby broccoli and therefore, no differences there either.
2020: This study was repeated in 2020 with the following differences: The cultivar 'Imperial' was used and was planted about 6 weeks later, on Aug 14. Data was collected and analyzed as described above. We added a second type of paper mulch, "WeedGuardPlus," so that the total number of treatments evaluated was seven.
| bare ground |
| black plastic |
| white plastic |
| straw |
| black paper |
| reflective silver |
| pink paper |
2021
"Evaluation of a push –pull system for diamondback moth management," Ana Legrand, UConn
A field evaluation tested the effectiveness of a push-pull system for managing the diamondback moth (DBM) - a key pest of brassica crops. The simultaneous use of trap and repellent plants constitutes a ‘push and pull system’ for insect pest management. This type of system is very effective against a number of insect pests. Many studies have examined only the single use of repellent or of trap crops against DBM. The experiment described below combines plants that have shown a degree of effectiveness either as repellent or as trap crops against the DBM.
Methods
The experiment was set at the Department of Plant Science Research and Teaching Facility, UConn and followed a completely randomized block design with 5 block replications and 5 treatments. Cabbage (Blue Thunder cultivar) was planted in 5.2 x 8 m plots that included tomatoes as a repellent crop in combination with the following trap crops: glossy collards, red Russian kale, upland and garden cress. Trap crops were arranged to form a 3 row perimeter around the main twelve cabbage crop rows. The tomato was planted as one row centrally located in the middle of 4 cabbage rows. Control plots consisted of only cabbage. All plants were planted with a 0.3 m spacing within the row and rows were 0.9 apart. There was a 3 m buffer spacing between plots. Weeds were managed by hand and through mechanical cultivation.
Ten randomly selected plants (trap crop and main crop plants) from each experimental plot were sampled weekly to quantify caterpillar presence. DMB eggs were not counted because they were easy to miss. However, all caterpillar stages were recorded including pupae. Plants were numbered to minimize resampling plants within consecutive weeks. Data were collected from June 30 to September 8 but due to heavy rainfall and/or flooding some weeks were not included in the analysis. Data were analyzed using analysis of variance (ANOVA with repeated measures) with the PROC Mixed procedure of SAS (SAS Institute, 2019).
Hypothesis 3: conservation biocontrol strategies attract predators and parasitoids of brassica pests, reducing pest population size and crop damage.
2018 & 2019
"Evaluations of Ammi majus as an insectary plant for cabbage caterpillar conservation biocontrol." This report is still in progress, as data are being summarized and analyzed now. This multi-year scientific study will be published and a full report will be published on our project website at: http://ag.umass.edu/vegetable/resources-services/brassica-pest-collaborative/research-reports-on-management-of-brassica
"Insectary flowers for attracting predators and parasitoids of cabbage aphid." This study was conducted at all three institutions (UNH, UMass, and UConn) and in 2018 and 2019. Every effort was made to standardize our protocols for experiment setup, data collection and analysis. A few summaries were written by each institution and are published on our project website, and a publication combining all the site years was written and submitted for publication in an academic journal. The methods are summarized below.
Cabbage aphid populations have been increasing in recent years and are now a major concern across New England. Brussels sprouts are especially susceptible, since aphids get into buds and are hard to reach with pesticide sprays. Therefore, alternative methods for controlling aphids are necessary. In other systems, interplanting with insectary plants (flowers that provide pollen and nectar and can serve as food and habitat for beneficial insects) is standard practice. One example of this is lettuce production in CA, where alyssum is planted every so often in the bed to support insects which are predators and parasitoids of aphid pests. Cabbage aphids are a little different than aphid pests of lettuce—they are larger and contain sulfur compounds that are not appealing to some predators—but nevertheless there is a large body of literature supporting the idea that predators (especially syrphid fly larvae) and parasitic wasps (especially the native braconid wasp, Diaretiella rapae) can impact cabbage aphid populations in the field. The purpose of this study was to compare several species of insectary flowers to see if any of them are more attractive to syphrids and parasitic wasps, and to identify which species of syrphids and wasps are present in New England.
Brussels sprouts were planted around the experiment in order to provide cabbage aphid hosts to help attract predators and parasitoids. Each flower was grown in a 15 sq. ft. plot and replicated four times. The insectary flowers tested were:
Alyssum 32 plants/plot
Buckwheat direct seeded at 6” spacing
Phacelia direct seeded at 12” spacing
Calendula 32 plants/plot
Dill 36 plants/plot
Cilantro 36 plants/plot
Ammi 32 plants/plot
Plants were direct-seeded or transplanted on July 13th, except Ammi majus which was planted on July 6th, and cilantro and dill which were planted on July 20th. The Phacelia never germinated so we have no data on that plant this year; in past years it was very attractive to a diversity of insects. To assess the relative attractiveness of each species of flower, we did timed observations in which we recorded the number of syrphids, small wasps, and other insects landing on flowers within a 1 square foot area for four minutes per plot. We then did sweep net sampling using a 15 in. muslin sweep net to collect insects within the plots and later characterized the number and types of insects collected and recorded information about the weather, time of day, and flowering activity. Over the winter, we identified wasps and syrphids as best as possible. In 2019 we focused on syrphid flies and did not collect wasp specimen because the wasps proved to be too numerous and difficult to ID. We intended to also collect syrphid fly larvae from CA colonies in order to rear them to adults in the lab and determine their species identity. However, because of low CA pressure in 2019, we were not able to achieve this outcome. We wanted to repeat this study in 2020 but were unable to get the permissions needed because of COVID19 restrictions.
Hypothesis 4-Integrated Approaches:
2020: We had planned to integrate some of these approaches in collaborative research in 2020 but due to the COVID-19 pandemic restrictions on hiring, travel, and in-person work we were unable to carry these out.
To see the full reports with figures please visit: http://ag.umass.edu/vegetable/resources-services/brassica-pest-collaborative/research-reports-on-management-of-brassica
Hypothesis 1: reduced-risk and organic-compatible pesticides effectively control brassica pest populations.
2018
"Foliar Insecticides for Control of Cabbage Flea Beetles (FB) in Cabbage and Pak choy,"
Plots treated with conventional insecticides Warrior II and Harvanta had significantly fewer flea beetles and less damage throughout the trial period. Assail was moderately effective in cabbage but not in pak choy. The residual activity of Assail appears to last only a short period (several days?) and that may explain why it was less effective on a fast-growing crop like pak choy—we observed many new pak choy leaves between treatment applications. OMRI-listed insecticides were less effective against cabbage flea beetle in these trials. Surround WP-treated cabbage had significantly lower numbers of flea beetle on plants, but the foliar damage was relatively high, inconsistent with the numbers seen. Application of Surround-WP on cabbage transplants was associated with stunted plant growth across all replications. Plants in these plots were comparatively smaller with less foliage and they failed to produce heads. The lower numbers of flea beetles in Surround-treated plots could be due to repellency from the kaolin clay coating to the newest leaves, but damage ratings, which were done on the entire plant, suggest feeding may be occurring where the residues wash off or beetles were choosing to feed on undersides of treated leaves.
Of the OMRI-listed insecticides, Entrust was most consistent in terms of reduction in flea beetle damage and improvements in yield and quality. It is important to note that the study area had a high flea beetle population at the time of the trial and the small plots were bordered by other less effective treatments and untreated plants, which would not be typical for a commercial setting where the entire field would be treated with a single insecticide with usually no untreated area. In such cases, the efficacy of some less effective products may be greater than that observed in small-scale trials. Near the end of the trial, collecting flea beetle damage data became more difficult due to presence of damage from other foliage feeding insects such as imported cabbage worm, cabbage loopers, and diamondback moth, since no insecticide was applied to control other insects (Harvanta, Entrust, and Warrior and to some extent Assail are generally effective to highly effective against these pests).
"Beneficial Nematodes to Reduce Flea Beetle (FB) Population Size"
There were no significant differences between any treatments, on any of the collection dates. This might be because we didn’t get the timing right (we would want the nematodes to be present when larvae are present in soil but are not too old) or because we did not have enough traps to detect small differences. We repeated this experiment using more traps to increase the chances that active nematodes are present when flea beetle larvae are at the correct life stage in 2019, results are described below.
2019
"Foliar Insecticides for Control of Cabbage Flea Beetles (FB) in Cabbage and Pak choy,"
Pretreatment cabbage flea beetle populations were extremely high in the study area and foliage feeding was started right after transplanting the 4 weeks old seedlings. As a result, treatment application was started within 72 hours of transplanting. Cabbage flea beetle populations were similar among treatment plots at the pretreatment counts on 8/26 (average 30.55 adult/plant). Plots treated with conventional insecticides Warrior II and Harvanta had significantly fewer flea beetles throughout the trial period. Entrust and Assail was moderately effective. The residual activity of Assail and Entrust appears to last only a short period (2 - 3 days) and that may explain why these two insecticides were less effective on a fast-growing crop like pak choy—we observed many new pak choy leaves between treatment applications. In 2018, we had found some of the OMRI-listed insecticides were partially (at some time-points) effective in reducing flea beetle damage but in 2019, because of the high population, the effect from the OMRI-listed material were not as evident in this trial. Although some treatments had significantly lower numbers of flea beetle on plants, the foliar damage was relatively high, inconsistent with the number of flea beetles seen on plants. The inconsistent numbers of flea beetles in plots could be due to repellency and/or lack of green foliage, but % foliage feeding data, which were done on the new growth, suggest more effectiveness of the treatments. Percent leaf area with feeding damage by flea beetles was significantly lower in plots treated with conventional insecticides (Assail, Warrior, and Harvanta) compared with untreated plants. Of the OMRI-listed materials Entrust reduced foliar damage significantly greater than the other OMRI-listed materials and to the untreated control. It is important to note that the study area had a high flea beetle population at the time of the trial and the small plots were bordered by other less effective treatments and untreated plants, which would not be typical for a commercial setting where the entire field would be treated with a single insecticide with usually no untreated area. In such cases, the efficacy of some less effective products may be greater than that observed in this particular trial.
Plant quality such as height, width and weight were generally higher in the effective treatments (Warrior, Harvanta, Assail, and Entrust) at least partly due to less flea beetle damage. Marketable quality was also generally higher in the effective treatments.
"Beneficial Nematodes to Reduce Flea Beetle (FB) Population Size"
As in 2018, there were no significant differences between any nematode or Entrust control treatments in 2019, despite doubling the sample size. The impacts of treatments on soil-dwelling stages of FB are inherently difficult to study in the field. We did see a flush of flea beetles emerge from traps and feel the method was working as designed, but we were not able to detect any significant reductions in FB numbers under any of the nematode or Entrust treatments.
"Organic and reduced-risk pesticides for control of cabbage root maggot"
Cabbage maggot pressure in the area was moderate with 46.25% plants in untreated control plots showing some levels of root damage. Overall infestation level was slightly lower in the 2019 season compared to that observed in similar trials over the past several years. Besides normal population fluctuations, an unusually wet and cool spring season might also partly explain the slightly lower cabbage maggot pressure.
There was a significant effect due to treatment, with the lowest levels of maggot-damaged plants in exclusion netting + black plastic mulch plots (> 98% roots undamaged), and black plastic mulch alone (>95% roots undamaged), followed by Lorsban (9.0%), Radiant (12.5%), and Verimark SC (15%). Entrust SC appeared to provide a significant if moderate level of control with nearly 70% undamaged roots. Control plants had 55% roots undamaged by cabbage maggot. Severity of root damage (0 – 10 scale, 0 = no damage, 10 = root completely consumed) was significantly lower in all insecticide and mulch treatments than in control plots , although the overall damage severity rating was minimal in the control plot averaging 1.21 out of 10. There was no phytotoxicity observed in any treatment.
Above-ground average stem diameter (N = 20/rep) for 4-week-old plants was significantly higher in plots covered with exclusion netting than in all other treatments. Climatic conditions such as temperature and soil moisture under the netting might have influenced greater plant growth. Among the seven treatments average head diameter at harvest (N = 20/rep) was not significantly different. However, compared with controls average cabbage head weight at harvest was significantly higher in all treatments with more than 80% undamaged roots (i.e. all except for Entrust).
There was moderate pressure in this trial from foliar-feeding insects, primarily crucifer flea beetle (Phyllotreta cruciferae) and lepidoptera (imported cabbage worm, Pieris rapae; cabbage looper, Trichoplusia ni). Plants in Lorsban 75WG, black plastic mulch only, and untreated control plots had significantly higher (about 2.75 - 3.0%) foliar damage (defoliation)from cabbage flea beetle and worms than other treatments. There was almost no defoliation (<0.10%) in plots treated with Verimark and exclusion netting. There was a small but significantly higher level of foliar damage (1. 1 – 1.2%) observed in plots treated with Entrust and Radiant. Cabbage head quality (based on feeding holes on head and 5 wrapper leaves) was significantly higher in plots treated with Verimark and exclusion netting. Marketable quality was also acceptable in plots with Entrust, Radiant and plastic mulch alone though the level of protection was significantly lower than where Verimark and exclusion netting were used. Foliar feeding damage was not controlled by Lorsban application and the level of damage was not significantly different from that in untreated control.
In our study planting cabbage under exclusion netting and/or over black plastic mulch may provide more than 95% root protection from cabbage maggot. Pre-transplant tray drench + one additional targeted spray application with Verimark 1.67SC and Radiant 1SC at 2-week interval may provide over 80% undamaged roots which is close to the protection from Lorsban 75WG (>90% undamaged roots).
2020
"Organic and reduced-risk pesticides for control of cabbage root maggot"
Cabbage maggot pressure in the area was comparatively higher than the past two years with 91.75% plants in untreated control plots showing some levels of root damage. Overall, the intensity of infestation (feeding size, number of tunnels etc.) was higher in the 2020 season compare to that observed in similar trials than the past year. Favorable weather, warmer winter, and timing of plantings might be partly contributed to the higher cabbage maggot pressure in the area.
There was a significant effect due to treatment, with the lowest levels of maggot-damaged plants in exclusion netting + black plastic mulch plots (92.5% roots undamaged), followed by Lorsban (67.5%), Verimark SC (58.75%), Radiant (43.75%), and black plastic mulch alone (37.5% roots undamaged). Overall performance of all treatments except exclusion netting was lower in 2020 than the past two years presumptively for high cabbage maggot pressure in the area (Figure 1). Treatment application timing and other variables such as soil moisture condition, tillage, soil type could be responsible for lower performance of some treatments. The control plants had only 8.75% roots undamaged by cabbage maggot. Severity of root damage (0 – 10 scale, 0 = no damage, 10 = root completely consumed) was significantly lower in all insecticide and mulch treatments than in control plots (3.26 out of 10). The overall damage severity ratings were relatively higher than the 2018 and 2019 in all treatments averaging between 0.61 – 1.39 (Figure 2). There was no phytotoxicity observed in any treatment.
Above-ground average stem diameter (N = 20/rep) for 4-week-old plants was significantly higher in plots covered with exclusion netting and Verimark treatment than in all other treatments (Figure 3). Among the treatments average head diameter and head weight at harvest (N = 20/rep) were also significantly higher in Verimark and exclusion netting plots (Figure 4 & 5). Climatic conditions such as temperature, soil moisture, and most part very low foliar damage from other insects might have influenced greater plant growth in the exclusion netting and Verimark treatment plots.
There was moderate pressure in this trial from foliar-feeding insects, primarily crucifer flea beetle (Phyllotreta cruciferae) and lepidoptera (imported cabbage worm, Pieris rapae; cabbage looper, Trichoplusia ni) (Figure 6 & 7). Plants in Lorsban 75WG, black plastic mulch alone, Radiant, and untreated control plots had significantly higher foliar damage (2.07 - 5.81% defoliation at 5 weeks from transplanting) from cabbage flea beetle and worms than other treatments. There was almost no defoliation (<0.10%) in plots treated with Verimark and exclusion netting. Though Radiant is an effective material for lepidopteran worm control, the application method used in this cabbage maggot experiment was entirely different from the worm control application. Marketable cabbage head quality (based on feeding holes on head and 5 wrapper leaves) was significantly higher in plots treated with Verimark and exclusion netting (Figure 8). Head quality was acceptable (good for consuming after discarding the damage portion) in the other plots. Foliar feeding damage was not controlled by Lorsban application and the level of damage was not significantly different from that in untreated control.
Hypothesis 2: cultural practices (e.g. netting, mulches, and residue management) disrupt pest life cycles and reduce crop damage;
2018
"Using Mulches to Reduce Flea Beetle Damage and Improve Crop Yield."
From the very beginning of the 2018 trial, we saw significant differences in flea beetle damage across the mulch treatments (Figure 2). The black plastic, paper, and reflective plastic mulches showed consistently less damage than other mulches or the bare ground control, but the reflective plastic mulch stood out as having the least damage of all, and the effect was highly significant and lasted for at least 6 weeks. All of the mulches improved plant growth relative to the bare ground plants, with straw and reflective silver mulches growing the tallest. Plant height was not directly correlated with flea beetle damage, but rather seems to correspond with soil temperature, which was cooler under these mulches.
Plants grown in reflective mulch were also more vigorous than bare ground plots. For other mulches, no consistent trend is evident; different mulches caused increased or decreased plant vigor at different timepoints. Mulches influenced both the high and the low temperature of the soil, with the bare ground tending to have the highest high and the lowest low, and mulches acting to modulate the temperature to varying degrees. Soil in the bare ground plots got hottest, followed by black and white plastics, then paper, then straw and reflective silver. During the night, bare ground soil also got colder than mulched plots, followed by paper, then straw and white plastic. Black and reflective mulches stayed warmest. Brassicas are cool-season plants, and prefer a cooler soil and air temperature, so lower soil temperature under straw or reflective mulch could partly explain increased plant growth and vigor observed in those plots.
At the end of the season, we harvested whole plants to assess overall plant growth, since broccoli crowns could not be harvested. Only the reflective silver mulch increased harvest weight, relative to the bare ground control.
2019
"Using Mulches to Reduce Flea Beetle (FB) Damage and Improve Crop Yield."
None of the mulch treatments affected FB damage or plant growth of bok choy, since it was so attractive to FB that all plants had severe damage and no differences could be distinguished. Furthermore, the bok choy pulled FB away from the broccoli experiment and pressure there was too low to distinguish any treatment effects.
2020
"Using Mulches to Reduce Flea Beetle Damage and Improve Crop Yield."
The results were similar to those seen in 2018, with reflective silver mulch producing plants that were more vigorous and higher yielding with lower flea beetle numbers and damage. However, the effect was not as pronounced, and straw mulch-grown plants also did very well in these measures.
2021
Evaluation of a push –pull system for diamondback moth management: The mean number of DBM caterpillars per cabbage significantly decreased when cabbage was planted with red Russian kale and glossy collards in combination with tomatoes. The mean number of DBM per cabbage averaged over seven weeks of data collection is shown in Fig. 1. Upland and garden cress in combination with tomato had a trend for lower numbers but more work is needed to adjust the density of these plants and to tease out other plant effects. The data collected on number of DBM on trap plants is being analyzed. The reduction of DBM caterpillars per cabbage for 2 trap crops used in combination with tomatoes indicate that there is the potential to identify successful trap plants to develop a push and pull system for DMB. This experiment will be repeated in 2022, though the SARE project will have ended.
Hypothesis 3: conservation biocontrol strategies attract predators and parasitoids of brassica pests, reducing pest population size and crop damage
"Evaluations of Ammi majus as an insectary plant for cabbage caterpillar conservation biocontrol."
This data is still being analyzed. When available, a full report will be published on our project website at: http://ag.umass.edu/vegetable/resources-services/brassica-pest-collaborative/research-reports-on-management-of-brassica
"Insectary flowers for attracting predators and parasitoids of cabbage aphid."
2018
The first flowers to open were from the Ammi plants, which were started earlier in the greenhouse, in late-July. Calendula, buckwheat and alyssum began flowering on August 3rd and dill and cilantro began flowering on August 23rd and September 4th, respectively. When we looked at the total number of syrphids from aphid-eating (aphidophagous) groups collected in sweep nets, the alyssum had by far the most, followed by dill and then cilantro and Ammi (Figure 2-L). These flowers all have small petals and very open habits or umbels. In order to compare all the flowers side-by-side, we must look only at dates on which all flower species were open, which was unfortunately only two dates in September (Figure 2-R). On these dates, again we see far more aphidophagus syrphids on alyssum, and just a few T. Marginatus on dill, Ammi, and buckwheat. The greatest diversity of syrphids was found on dill.
Of the aphidophagus syrphids collected, Toxomerus marginatus was by far the most common; others we collected included Taxomerus germinatus, Melanostoma mellinum, Allograpta obliqua, and a Sphaerophoria species. When we looked at T. marginatus over time, its numbers began to increase in early-September and then plummeted in late-August, as weather became gray, windy, and rainy. When the sun came out again in October, we started collecting large numbers again. This species seems to be present during most of the fall brassica growing period and would be a useful species to continue to try to attract into our brassica fields.
Our collection of small and potentially parasitic wasps was quite large and diverse. These specimen turned out to be much more difficult to identify to species or even to genus than the syrphids. At least several of those we collected in large numbers were braconids or ichneumonids, which are both groups known to be parasitoids of vegetable pests, but others are from groups that parasitize the parasitoids (hyperparasitoids), making things more complicated. We positively identified D. rapae, the native parasitoid of cabbage aphid, in our collections, and we also observed it hatching out of mummified aphids collected from the field. We collected the most D. rapae from Ammi majus, perhaps indicating a preference for that flower relative to other flower species tested (Figure 5). We believe that another wasp we collected often is a species in the genus Alloxysta, which is a genus of hyperparasitoids of braconid and apheliniid wasps. This wasp visited all of the flowers, but was collected in greatest numbers from the Ammi and alyssum.
2019
Results were similar in all locations. Alyssum, buckwheat, cilantro, and dill had greater hoverfly densities than calendula, phacelia, and fennel. Alyssum attracted the cabbage flea beetle and calendula attracted imported cabbage worm moths, but not at economically damaging levels. Fennel did not flower. In particular, alyssum was found to be a low maintenance plant that hosts the most prevalent aphid-eating hoverfly species (Toxomerus marginatus) from July until frost.
Hypothesis 4
no data to report
Hypothesis 1: reduced-risk and organic-compatible pesticides effectively control brassica pest populations
2018
"Foliar Insecticides for Control of Cabbage Flea Beetles in Cabbage and Pak choy,"
Harvanta 50SL and Warrior II provided the best protection from flea beetles in both cabbage and pak choy. Assail provided intermediate efficacy and of the OMRI-listed materials tested, Entrust showed consistent reductions in flea beetle damage and increases in yield measures. Some of the OMRI-listed materials showed some efficacy on some dates but were not as effective or as consistent as Entrust.
"Beneficial Nematodes to Reduce Flea Beetle Population Size"
As tested, beneficial nematodes did not have a measurable effect on flea beetle survival in the soil in either study year. Furthermore, while the nematodes may have some effects on underground stages of flea beetles, growers should be aware that adult beetles are very mobile and will keep coming into the field from other fields or weedy areas.
"Foliar Insecticides for Control of Cabbage Root Maggot in Cabbage and Pak choy."
Pre-transplant tray drench + one additional targeted spray application with Verimark 1.67SC may provide moderate to high level of control. The efficacy of Radiant 1SC and Entrust was variable mostly at moderate level. The efficacy of insecticide Lorsban 75WG was also variable between 68 – 92% undamaged roots. We believe cabbage maggot control from some of the effective insecticides also depends on application timing, soil type, irrigation, and population pressure of the area. Control success may vary between moderate to good level. Continued research is necessary for further information.
Hypothesis 2: cultural practices (e.g. netting, mulches, and residue management) disrupt pest life cycles and reduce crop damage;
"Using Mulches to Reduce Flea Beetle Damage and Improve Crop Yield."
Reflective silver mulch had the least flea beetle damage and plants were taller and more vigorous, and had significantly higher yields than plants grown in other mulches or in bare ground. This may be due to reduced plant stress from cooler soil temperature and more temperature buffering (lower highs and higher lows), or the reflected light may disorient or repel flea beetles, or it may be due to a combination of factors. The additional cost of the reflective silver mulch ($11/100 row ft compared to $3/100 row ft for black plastic) may be worth the investment, since a significant increase in plant growth and yield was observed. Furthermore, reduced feeding by flea beetles may contribute to reductions in black rot and Alternaria, since flea beetles are known to spread these diseases. Our 2020 results seem to validate this approach, but the trend was not as strong in 2020. When repeated with bok choy there was no effect of mulch on FB damage or plant growth, since that crop is so attractive to FB throughout its life.
"Organic and reduced-risk pesticides for control of cabbage root maggot"
Based on the past three years of study, planting cabbage under exclusion netting and over black plastic mulch may provide more than 95% root protection from cabbage maggot. Black plastic mulch alone was provided better control in 2019 but with the high maggot population in 2020, this treatment was not effective as expected.
Pre-transplant tray drench + one additional targeted spray application with Verimark 1.67SC may provide moderate to high level of control. The efficacy of Radiant 1SC and Entrust was variable mostly at moderate level. The efficacy of insecticide Lorsban 75WG was also variable between 68 – 92% undamaged roots. We believe cabbage maggot control from some of the effective insecticides also depends on application timing, soil type, irrigation, and population pressure of the area. Control success may vary between moderate to good level. Continued research is necessary for further information.
Hypothesis 3
"Evaluations of Ammi majus as an insectary plant for cabbage caterpillar conservation biocontrol."
This report is incomplete at the time of writing this final report. If the data analysis is completed in the future, a full report will be published on our project website at: http://ag.umass.edu/vegetable/resources-services/brassica-pest-collaborative/research-reports-on-management-of-brassica
"Insectary flowers for attracting predators and parasitoids of cabbage aphid."
This long-term regional survey for predators and parasitoids of cabbage aphids was a big success, with all three cooperating institutions developing shared protocols for planting, observing, and collecting beneficial insects in brassica fields. We identified many aphidophagous syrphids and parasitic wasps collected from insectary flowers, and determined that many are common across states. The most common aphidophagous syrphid species across states was Toxomerus marginatus. The most attractive to syrphid flies were dill, cilantro and alyssum while Ammi majus was most attractive to the parasitoid D. rapae. One challenge we encountered was that we collected such a large number and diversity of wasps that we had difficulty identifying all of them. Another challenge was erratic CA pressure across study years. In 2019 we attempted to collect aphid mummies from farms across New England and characterizing only wasps that hatch out of these mummies, in order to narrow down our survey to include only these species of wasp. We also attempted to collect syrphid fly larvae from CA colonies in order to determine which species of syrphid larvae are actively foraging on CA in the field but because of low CA pressure regionally we were unable to accomplish this goal.
Results of this study have been submitted for publication in the journal Biocontrol.
Hypothesis 4
Integrated approaches are critical to successful management of multiple, perennial pests in brassica crops. However, these studies are hard to set up, difficult to manage, and the results are often less exciting than studies on new, highly effective strategies. Growers use these approaches all the time--combining use of crop rotation with chemical control and exclusion netting, for example--but do not have the benefit of an untreated control to see how bad pest damage could be without these many strategies of small effect working synergistically to reduce pest numbers and damage. We hope to work on this in the future, and to document the costs of different approaches, including the costs of not controlling insect pests well.
Education
Education on biology and management of brassica pests was accomplished primarily through a series of online webinars in winter of 2019, and a follow-up webinar in April of 2021. In addition, the project team: hosted field days; wrote factsheets, newsletter articles, pest alerts, and research summaries; gave presentations; and spoke on podcasts. Much of this content was uploaded to a project website hosted by UMass: https://ag.umass.edu/vegetable/resources/brassica-pest-collaborative. Webinars and field days provided in depth training on pest biology and management, and showcased ongoing research. Participants expressed increases in both knowledge and confidence in implementing new pest management strategies. We used evaluations and surveys to document impacts.
Specific Activities:
A phone and web-based Brassica Pest Collaborative (BPC) was piloted during 2018 and 2019, through which Extension educators, ag service providers, and growers could discuss current issues in brassica pest management. The idea was that a weekly call would give growers a way to connect with each other and the Extension/research team to improve pest scouting, identification, and ultimately their brassica pest management. However, we were not able to get a critical mass of interest or activity in an email forum and we instead got the sense that our current outlets for pest alerts and management tips (Vegetable Notes weekly newsletter, LI Fruit and Veg Update weekly newsletter, Instagram, and Facebook) were enough, and growers did not want an additional email or phone commitment. Feedback from the advisory board led us to develop a series of webinars, described below.
Five webinars on biology and management of the major brassica pests were hosted live during the winter of 2019, and recordings were posted online for later viewing. Topics and format of the webinars were identified via an initial project survey and through the advisory board. Five such webinars were hosted during the winter of 2019 and were well attended live, and have been re-watched online many times (68-1600 views per video for a total of 4,519 views).
In 2021, a webinar including lessons learned and tips and tricks for managing brassica insect pests was held, and a related "tip sheet" was published. The recording of this summary webinar has been viewed 108 times. Growers who attended this workshop were followed-up with in the fall to determine if they implemented any strategies and if so, were they effective. A survey of these and other participating growers was completed in fall of 2021 and results are summarized below.
The project team had planned to work intensively with individual growers to answer pest management questions and provide follow-up. Due to the COVID-19 pandemic in 2020, this plan was disrupted. We attempted to do more in-person in 2021 but were by then overcommitted. In total we provided direct technical assistance with 64 growers over the 4-year project.
A survey was conducted with growers and ag service providers who participated in BPC activities, in order to assess impacts of our education program on brassica yield, quality and profits.
Milestones
1. 1500 farmers receive information about project objectives, resources, and educational activities including free e-alerts and phone-based or podcast-style education from the Brassica Pest Collaborative via our established Extension newsletters and email networks. May 2018.
1500
100
1730
288
May 31, 2018
Completed
June 30, 2018
Over the course of the project, we learned that our current Extension newsletters are an effective way to communicate timely pest alerts with growers, and there was no need to "reinvent the wheel." The email list serve was difficult to manage and so we instead relied on our Extension newsletters to spread the word about webinars, field days, and other project activities.
2. 300 farmers and 25 agricultural service providers join Brassica Pest Collaborative and/or access project webpage and educational resources and increase their knowledge of brassica pest biology, pest management, and ongoing research efforts and results. Ongoing from March 2018 to March 2021.
300
25
7328
150
March 31, 2021
Completed
November 01, 2021
The BPC email list serve was not a very effective means for communicating directly in-season with growers. There were 12 threads total going out to 47 members in 2018. Instead of email, we used our usual means for distributing brassica related pest alerts, Vegetable Notes, which reaches 2,884 growers, gardeners, and ag service providers. There are approximately 14-35 brassica pest alerts per season in this publication. In addition, we used our program Instagram pages to reach out to growers and ag service providers about our research activities in the season. Becky Sideman's "Sideman Lab" page has 541 followers and had 12 related posts in 2019. Sue Scheufele's "UMass Vegetable Team" Instagram page has 201 followers had 10 related posts in 2019.
Our website, "Brassica Pest Collaborative," has been accessed 1,675 times, 1,492 of those representing unique views from different computers. This website houses factsheets, research reports and our webinar series videos.
The webinars, which represent our main educational output, were hosted from Jan-March 2019 and had the following attendance, totaling 2,733 growers, gardeners, and ag service providers across the Northeast region. Recordings of these webinars posted on our project website have been viewed from 68-1,600 times per video, with a total of 4,519 subsequent views to date.
Cabbage Loopers and Diamondback Moth: 57 attended, 1,600 subsequent views
Cabbage Aphids: 55 attendees, 755 subsequent views
Flea beetles: 47 attendees, 543 subsequent views
Cabbage Root Maggot: 29 attendees, 1,400 subsequent views
Imported Cabbageworm and Cross-Striped Cabbageworm: 43 attendees, 113 subsequent views
All of the recorded webinars are available for viewing here: https://ag.umass.edu/vegetable/resources/brassica-pest-collaborative
Webinar attendees were surveyed after each program and a few highlights are listed below:
Cabbage Loopers and Diamondback Moth: Knowledge increased on average from 2.56 to 4.13 (1-5 scale) and growers rated their interest in adopting a new practice they learned about an average of 4.2 out of 5. One grower wrote they took home this message: "Will try to be more diligent about scouting, treating regularly if needed, and record keeping."
Cabbage Aphids: Knowledge increased on average from 2.89 to 4.28 (1-5 scale) and growers rated their interest in adopting a new practice they learned about an average of 4.1 out of 5. One grower wrote they took home this message: "I plan to implement weekly checks for cabbage aphids, instead of just doing it when I have time." Another wrote: "Insectary plants was a new concept for me."
Flea beetles: Knowledge increased on average from 3.1 to 4.1 (1-5 scale) and growers rated their interest in adopting a new practice they learned about an average of 3.8 out of 5. One grower wrote they took home this message: "Will try new products to control Flea Beetles." Another said "Thank you !! This was a good series."
Cabbage Root Maggot: Knowledge increased on average from 2.75 to 4.0 (1-5 scale) and growers rated their interest in adopting a new practice they learned about an average of 3.6 out of 5. One grower wrote they took home this message: "being on top of degree days and knowing when to scout!" Another wrote: "Multiple generations through the growing season. Surprised how effective exclusion is".
Imported Cabbageworm and Cross-Striped Cabbageworm: Knowledge increased on average from 2.7 to 4.3 (1-5 scale) and growers rated their interest in adopting a new practice they learned about an average of 4.2 out of 5. One grower wrote they took home this message: "I am definitely going to plant herbs and flowers to attract more beneficial insects. Also, now I'll know what I'm looking at when I see it!" Another wrote: "This talk was very clear and the visuals were great. I appreciate hearing where research is headed."
BPC researchers also wrote 14 factsheets and newsletter articles between 2018-2021.
In 2021 we conducted another webinar, "Practical Recommendations for Managing Insect Pests of Brassicas" which had 81 live attendees and was watched another 108 times subsequently. We also published a related "Brassica Insect Pest Management Tip Sheet"--a one page resource including our top management recommendations--that is published on our website. This webinar and factsheet provide a summary of recommendations based on our research findings and experience working with growers and observing our research plots.
Furthermore, Scheufele participated in two podcasts related to brassica pest management. One trade journal article was written summarizing the Vegetable Beet Podcast episode featuring brassica pest research updates and was published in Country Folk Grower, and another trade journal article was written summarizing our 2021 webinar and is published in Vegetable Growers News.
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Scheufele, S.B. 2021. Black Rot Management and Insect Pests of Brassicas. Vegetable Beet Podcast, UMN Extension. Online: http://www.glveg.net/listen. September 1, 2021
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Scheufele, S.B. 2020. Managing Cabbage Aphids and Cucurbit Downy Mildew. Vegetable News Podcast, Cornell Eastern New York Horticulture Program. Online: https://enych.cce.cornell.edu/podcasts.php. September 1, 2020.
- Hoidal, S. Scheufele, B. Dutta, T. Björkman. Learning to grow broccoli with new challenges. GLVPN Veg Connections. Vegetable Growers News. Volume 55, Issue 11. November 2021.
- Sonja Heyck-Merlin. Beware the buggers. Country Folk Grower, May 31, 2021. https://cfgrower.com/beware-the-brassica-buggers/
Lastly, BPC researchers gave a total of 39 additional presentations for grower, ag service provider, gardener, scientist and student audiences reaching a total of 2,953 individuals.
3. 150 growers attend field days and increase their knowledge and confidence in implementation of ecologically based management strategies for reducing impacts of brassica pests and observe ongoing research trials. October 2021.
150
359
52
October 31, 2020
Completed
April 14, 2021
2018
- F. Zaman and D. Gilrein. 2018 Long Island Agriculture Forum, January 11, 2018 Riverhead, NY: Diamondbacks, Earworms, Cabbage Maggot and Other Problem Pests; 85 vegetable growers attended.
- B. Sideman and A. Harris. Season extension and specialty crop research at UNH. Aug 2018. Durham Farm Day. Durham, NH; 45 gardeners and growers attended.
- S. Scheufele. Alternative strategies for managing cabbage aphid in fall brassicas. UMass Extension Agricultural Field Day 2018. South Deerfield, MA, August 2018; 45 growers and ag service providers attended. Survey respondents reported: 34.6% increase in knowledge about using mulches to reduce flea beetle damage and 72% were likely to implement this on their farms; and 22% increase in knowledge about using insectary habitat to attract beneficial insects for cabbage aphid control and were 55% likely to implement this on their farms.
2019
- On 9/4/2019, a cover crop and vegetable research twilight meeting/demonstration program was organized in the project site at the Cornell University Long Island Horticulture Research and Extension Center (LIHREC). 34 attendees were participated in the program.
- A. Harris. Using insectary plants to promote biological control of pests. 6th Annual Farm Day. 17 Aug 2019. Woodman Horticultural Research Farm, University of New Hampshire, Durham. (45 farmers, researchers, community members)
- S. Scheufele. 8/20/2019 Vegetable IPM Research Twilight Meeting: UMass Research Tour and Pest Roundtable UMass Extension South Deerfield, MA 45 attendees
- A. LeGrand. Vegetable IPM Field Workshop, August 13, 2019. 25 attendees. Attendees on average rated their before- and after-program knowledge as follows (1-5 rating scale with 5 being most knowledge):
Brassica insect pest management topics Before After
Insect life cycles & identification 2 4
Insect Monitoring 2.8 4.1
Insectary Plant Use 2.3 4.1 - S. Scheufele. 12/19/19. Updates from the Brassica Pest Collaborative. New England Veg and Fruit Conference. 50 growers attending.
In 2020, none of the scheduled field days were able to be held due to the COVID-19 pandemic but the following virtual talks were given:
-
Faruque Zaman; “Alternative options for cabbage maggot and flea beetle control in crucifer crops”; 39th Long Island Annual Agriculture Forum; Riverhead, NY 11901; January 8 - 9, 2020 - 90 attendees.
-
Faruque Zaman; “Cabbage maggot and flea beetle control in crucifer crops - alternative options”. 2020 CCE-ENY Fruit and Vegetable Conference. Albany, NY; February 26, 2020 - 86 attendees.
-
Faruque Zaman; “A World without Lorsban”. Great Lake Vegetable Production Network (GLVPN), MSU; August 19, 2020 - 15 attendees (virtual)
2021
On April 14, 2021 we hosted an online workshop entitled "Practical Tips for Managing Brassica Insect Pests" with 81 live attendees (34 growers, 27 gardeners, and 12 ag service providers) and 102 subsequent views. The purpose of this webinar was to highlight recommendations we make to commercial growers we would have worked with in person in 2020-21 but COVID-19 disruptions significantly reduced our capacity to do this in both year, so we used the virtual format to try to reach a wider audience and then follow-up with those growers, and other participants, after the 2021 season to see if any improvements in yield or quality were achieved.
Additionally, BPC project team gave the following relevant presentations in 2021:
-
Legrand, A. 2021. Using biological control for greenhouse insect pest management. CNLA Winter Symposium and Expo. February 28, 2021. Online conference.
-
Legrand, A. 2021. Using biological control for greenhouse insect pest management. Connecticut and Rhode Island NOFA Winter Conference, March 13 2021. Online conference.
4. 100 growers express interest in implementing one of the strategies identified as improving pest control and crop yield such as adopting a weekly scouting program, planting insectary plots on their farms, or incorporating reduced-risk pesticides into their spray programs. March 2019.
100
549
May 01, 2021
Completed
November 01, 2021
Growers who participated in webinars and field days were surveyed for their interest in implementing new practices as a result of our educational activities. Growers surveyed at a UMass field day were 55% likely to implement a new practice, while webinar attendees were, on average, 40% likely to implement a new practice. Given that we reached 1,372 individuals through field days and webinars so far, a conservative estimate of grower willingness to adopt new practices to control brassica insect pests is 549 growers.
In 2021, we tried to reach growers using a virtual format, to share our recommendations online in the spring, in time for grows to adopt new practices and document their changes in brassica yield and quality throughout the growing season. We conducted a survey of these and other BPC participants at the end of the growing season in November of 2021. The results are summarized below in the performance target section.
5. 75 growers receive support documents including factsheets, scouting sheets, and other resources and/or receive support via BPC phone calls. September 2019.
75
64
12
September 30, 2019
Completed
November 01, 2021
In a 2019 survey of LI brassica growers, among the 6 respondents, five growers have responded positive (at a scale of 4 out of 5) for adoption of the new brassica pest management techniques developed from this project. Two growers partially adopted the exclusion netting techniques for controlling cabbage maggot and other pests. Consultation through demonstration and power point presentation. Impacting ~10 acres.
Ana Legrand worked with 3 growers in 2019 to implement new practices. One grower commented that this was the best quality brassica crop he has obtained by implementing the practice (protekt net).
Sue Scheufele worked with 5 growers in 2018 and 2019 to implement new practices including use of Surround on transplants, regular scouting technique and thresholds, spray timing and coverage, use of insectary plantings, identification of beneficial insects, use of insect netting. Impacting ~25 acres.
Becky Sideman helped one grower identify a brassica problem (black rot), visited their farm, and provided in-person and followup consultation with info about how to manage black rot in the future, including seed treatments. Since this only pertains to future seed purchases, there is no measurable impact yet. Identification did result in fewer pesticide applications, since the grower was uncertain as to the cause of the problem and was treating with several pesticides to manage the problem. She also repeatedly put out info about brassica pests, and specifically reached out to growers who had previously had trouble with cabbage aphid – and did not get any participants who were having trouble and needed assistance.
In 2021, we tried to reach growers using a virtual format, to share our recommendations online in the spring, in time for grows to adopt new practices and document their changes in brassica yield and quality throughout the growing season. Of the 81 live attendees, 34 were growers. These growers received follow-up via email and completed an impact survey at the end of the project.
We also worked one-on-one with small group of growers (at least 13 received at least one contact, 3 received multiple follow-up consultations) to provide recommendations and support. We conduced a survey of these and other webinar and field day participants in November of 2021.
Milestone Activities and Participation Summary
Educational activities:
Pest Alerts: 68 related alerts in 2 newsletters (Veg Notes and LI Fruit and Vegetable Update, 2,884 and 225 subscribers, respectively).
Instagram posts: 9
Email list-serve threads: 10
Participation Summary:
Learning Outcomes
Attendees surveyed at a 2018 field day at UMass reported: 34.6% increase in knowledge about using mulches to reduce flea beetle damage and 72% were likely to implement this on their farms; and 22% increase in knowledge about using insectary habitat to attract beneficial insects for cabbage aphid control and were 55% likely to implement this on their farms.
Vegetable IPM Field Workshop, August 13, 2019. Attendees on average rated their before- and after-program knowledge as follows (1-5 rating scale with 5 being most knowledge):
Brassica insect pest management topics
|
|
Before |
After |
|
Insect life cycles & identification |
2 |
4 |
|
Insect Monitoring |
2.8 |
4.1 |
|
Insectary Plant Use |
2.3 |
4.1 |
Nuts and bolts of Farmscaping for beneficial insects. NOFA Winter Conference. Feb. 23, 2019. 93% of attendees indicated an increase in knowledge.
In a 2019 survey conducted with brassica grower on Long Island, among the 6 respondent, five growers have responded positive (at a scale of 4 out of 5) for adoption of the new brassica pest management techniques developed from this project.
Our webinar series resulted in consistent increases in knowledge, from 20-31% increases in knowledge of pest biology and management practices, on average.
Our final webinar in 2021 reached 34 growers and 12 ag service providers and that audience reported a 23% increase in knowledge after participating. Participants were 89% likely to implement something they learned in their work, and rated the online learning experience an 88/100.
In November of 2021 we surveyed any grower who had participated in our online workshops, attended field days (if contact info provided), had a 1-on-1 consultation, and received >68 related pest alerts in our newsletters. The results relative to changes in knowledge and skills are summarized below in the Performance Target Outcome Narrative.
Performance Target Outcomes
Target #1
50
adopt or improve ecological pest management approaches including scouting, cultural practices, conservation biocontrol, and use of reduced-risk pesticides
500 acres
reduced crop damage, increased marketable yield, and increased annual gross revenue (+$500,000)
64
adopted or adjusted at least one new practice
87.2 acres
growers report improved pest control, crop quality and improved marketable yield
Before our outreach could begin, the Office of Research & Engagement at UMass had to review all of our outreach plans and tools to ensure compliance with human subjects research and be approved by the Institutional l Review Board (IRB). This resulted in a significant delay of our planning and implementation of our outreach objectives. We did design a project announcement that went out to our stakeholder groups and included a survey and way for growers to sign up for different educational activities.
The survey was completed by just 16 growers from across the region and Nebraska, but our results indicated that: flea beetles were the biggest pest issue on greens and radishes, cabbage aphid is the main pest of Brussels sprouts, and caterpillars are the biggest pests of cabbage; respondents were most interested in interview-style educational opportunities, and in-depth discussion and description of pest biology and management; and respondents were most interested in learning how to use resistant varieties, biocontrols, and conservation biocontrol practices to control pests.
- In 2018, five growers expressed interest in participating as collaborators, implementing a strategy on their farm and documenting changes in pest pressure and crop damage and yields, but unfortunately, we were unable to assist them this year because of the delays in planning caused by the IRB review.
- In 2019, we were able to work directly with 15 growers on approximately 35 acres. These growers learned to scout, use thresholds to time sprays, improve spray coverage, improve selection of spray materials, plant insectaries, use insect netting, and use surround on transplants. In 2020 we will plant to work with these growers to collect better documentation of the economic costs and benefits of these practices, and demonstrate changes in yield, quality, and/or profits.
- In 2020, despite restrictions on working in-person due to COVID-19, we worked in depth with three brassica growers on pest management topics including material selection and timing of sprays, organic cabbage root maggot control, disease management and avoiding phytotoxicity when using copper on brassicas, and fertility questions.
- In 2021, the project team worked with at least 13 growers to provide technical assistance and support these growers to adopt or adjust their pest management practices to improve pest control, crop quality and yield. We also stayed in contact with 34 growers who attended our spring '21 webinar and sent them an impact survey in November '21.
The survey conducted in fall of 2021 assessed changes in knowledge and behavior among growers who participated in BPC outreach activities. We sent the survey to growers who attended online or in-person webinars and field days, and those we worked with one-on-one. We also sent the survey to growers who receive our newsletters/pest alerts, but overwhelmingly the people who completed the survey attended workshops and received technical assistance, and only 33 growers completed the whole survey. The data are summarized below.
- Brassica acreage managed ranged from 300 sq ft to 35 acres
- Average of 3.76 acres
- Total acreage 124.3
- 32 respondents (97%) participated in at least one of the following outreach efforts:
- 12 (36%) attended at least one webinar
- 11 (33%) did receive one-on-one technical assistance
- 18 (55%) did use resources from the BPC website such as scouting sheets, factsheets, research reports, or pest ID sheets
- 29 (88%) received pest alerts
We asked respondents how much they increased knowledge in the following topics:
-
- How to ID a certain brassica pest or its damage
- Pest life cycles
- How to scout for a pest
- Cultural practices to control pests e.g. crop rotation, mulches & netting
- Biological control e.g. attracting or releasing beneficial insects
- Chemical control options e.g. products, timing, spray coverage
On average, across all topics, 60% of respondents reported they increased their knowledge at least slightly. These individuals collectively manage 66.2 acres.
The largest reported increases in knowledge were on the topics of chemical control options and how to scout for a pest – 33% of respondents reported they increased their knowledge very much on both of those topics.
We asked respondents if they adopted or adjusted and of the following practices:
-
- Improve spray timing
- Choose a different insecticide
- Add a spreader/sticker
- Change your nozzles
- Use exclusion netting
- Rotate crops
- Use a NEWA model or bio-indicator
- Use a trap crop
- Scout regularly
- Use a threshold for spraying
- Continue treating as long as thresholds are exceeded
- Incorporate residues quickly after harvest
- Plant an insectary
- Use mulches
- Use beneficial nematodes
Practices were adopted or adjusted 107 times by 27 (82%) respondents
Of those who adopted or adjusted a practice, 42% reported that it was successful and 44% reported that they would try it again.
Comments about how practices may have changed and how successful or not those changes have been?
-
- Given the number of years I have been doing this, many practices were already adopted
- I used entrust for flea beetle populations twice this year. I found it to be immensely helpful!
- We did a better job controlling root maggot than we ever have by scouting/timing applications better.
- We prevented / controlled alternaria with some success thanks to timely article in pest message . We were also able to hold it off of late plantings using biological materials thanks to the control recommendations in the U Mass vegetable newsletter.
-
I feel confident saying that you and your team helped me with the following brassica related things in the last 4 years. We have about 1.5 to 2 acres of brassicas in any given year (lots of successions). We have fewer losses to pests now, and are very grateful for it!
- how to scout for caterpillars
- timing of sprays
- identifying a new pest/damage
- switching from pyganic to entrust for flea beetles
- using surround to protect seedlings from flea beetles
- using exclusion netting
- using a spreader/sticker for insecticide sprays
- general scouting support and reporting pest problems
We asked if these changes in practices resulted in improved pest control, crop quality, yield, or profits:
- 23 people (70%) managing 101 acres reported improved pest control ranging from 3-80% increase with an average of 43.4% increase in pest control
- 19 people (58%) managing 59.6 acres reported improved crop quality (mean = 49.17% improvement)
- 18 people (55%) managing 61.7 acres reported improved marketable yield of on average 44.24%
- 14 people (42%) managing 50.6 acres reported increased profits (mean = 42% increase)